Ion eluting unit and device loaded with same

ABSTRACT

An ion elution unit generates metal ions by applying a voltage between electrodes. Terminals are formed integrally to the electrodes. The terminals protrude downward through the bottom wall of the casing of the ion elution unit. The space between the electrodes becomes narrower from the upstream side to the downstream side along with the water current flowing through the inside of the casing. The casing has a water inlet and a water outlet, the cross-sectional area of the water outlet is smaller than that of the water inlet. The water outlet is disposed at the lowest level in the inner space of the casing. The cross-sectional area of the inner space of the casing gradually decreases from the upstream side to the downstream side.

TECHNICAL FIELD

The present invention relates to an ion elution unit for eluting metalions having an antimicrobial effect into water, and also relates to anappliance, in particular a washer, that uses water mixed with metal ionsgenerated by such ion elution unit.

BACKGROUND ART

When laundry is washed in a washer, it is common to add a treatmentsubstance to water, in particular, to rinsing water. Typical examples ofsuch treatment substances include softening and starching agents. Inaddition to these, in recent years, the demand has been increasing fortreatment whereby laundry is subjected to antimicrobial treatment.

From the hygienic point of view, it is desirable to hang laundry in thesun to dry. However, in recent years, with the increase in the number ofwomen who go to work, and with the increase in the number of nuclearfamilies, there have been an increasing number of households where noone is at home in the daytime. In these households, there is no choicebut to hang laundry indoors to dry. Even in households where someone isat home in the daytime, in a rainy weather, there is no choice but tohang laundry indoors to dry.

As compared with hanging laundry in the sun to dry, hanging it indoorstends to promote growth of bacteria and mold in laundry. This tendencyis marked particularly when it takes time to dry laundry, as whenhumidity is high, such as in a rainy season, or when temperature is low.As the amount of bacteria and mold increases, laundry may become smelly.For this reason, in households where there is usually no choice but tohang laundry indoors to dry, there is a high demand for antimicrobialtreatment of textile articles for the purpose of suppressing growth ofbacteria and mold.

Nowadays, many clothes are available that have previously been treatedwith antimicrobial/deodorizing or antifungal treatment. However, it isdifficult to replace all the textile articles in a household with thosepreviously treated with antimicrobial/deodorizing treatment. Moreover,even with such textile articles, as they are washed repeatedly, theefficacy of antimicrobial/deodorizing treatment wears off.

Conceived under these circumstances was the idea of treating laundrywith antimicrobial treatment every time it is washed. For example,Japanese Utility Model Laid-Open No. H5-74487 discloses an electricwasher furnished with an ion generator that generates metal ions, suchas silver ions or copper ions that exert a sterilizing effect. JapanesePatent Application Laid-Open No. 2000-93691 discloses a washer thatgenerates an electric field with which to sterilize cleaning fluid.Japanese Patent Application Laid-Open No. 2001-276484 discloses a washerfurnished with a silver ion adding unit that adds silver ions tocleaning water.

DISCLOSURE OF THE INVENTION

An object of the present invention is to provide an ion elution unit forgenerating metal ions having an antimicrobial effect in which metal iongeneration efficiency is high. Another object of the present inventionis to provide an appliance, in particular a washer, that uses watermixed with metal ions generated by such an ion elution unit to avoidadverse effects brought about growth of bacteria, and that permits theion elution unit to operate efficiently.

To achieve the above object, according to the present invention, an ionelution unit is constructed in the following manner. In an ion elutionunit generating metal ions by applying a voltage between electrodes, aspace is secured between the electrodes and the inner surface of thecasing of the ion elution unit. With this construction, the electrodesare supported with a space secured between them and the inner surface ofthe casing. This prevents a metal layer from growing from the electrodesto the inner surface of the casing and eventually causingshort-circuiting between the electrodes themselves.

According to the present invention, in the ion elution unit constructedas described above, the interval between the electrodes is so set as tobecome narrower from the upstream side to the downstream side withrespect to the water current flowing through the inside of the casing ofthe ion elution unit. With this construction, the interval between theelectrodes is so tapered as to become increasingly narrow from theupstream to the downstream side. This permits the electrodes to liealong the water current, and thus, even when they wear and become thin,they are not prone to chatter or chip. Moreover, the electrodes areunlikely to be so heavily deformed as to cause short-circuitingtherebetween.

According to the present invention, in the ion elution unit constructedas described above, terminals that are so laid as to run from theelectrodes out of the casing of the ion elution unit are disposed on theupstream side with respect to the water current flowing through theinside of the casing, and a supporting portion for supporting thedownstream-side parts of the electrodes is formed on the inner surfaceof the casing. With this construction, the electrodes are supportedfirmly both on the upstream and downstream sides, and thus do notvibrate in the water current. This makes the electrodes unlikely tobreak as a result of vibration.

According to the present invention, in the ion elution unit constructedas described above, a water inflow port and a water outflow port areformed in the casing of the ion elution unit, and the outflow port isgiven a larger cross-sectional area than the inflow port. With thisconstruction, the outflow port of the ion elution unit has a smallercross-sectional area, and hence a higher flow passage resistance, thanthe inflow port thereof. Thus, the water that has entered the casingthrough the inflow port fills the interior of the casing without leavinga lump of stagnant air, and thus completely immerses the electrodes.This permits no part of the electrodes to be left uninvolved in thegeneration of metal ions and remain uneluted.

According to the present invention, in the ion elution unit constructedas described above, the cross-sectional area of the interior space ofthe casing gradually decreases from the upstream side to the downstreamside. With this construction, not only is the cross-sectional area ofthe outflow port smaller than that of the inflow port, thecross-sectional area of the interior space of the casing graduallydecreases from the upstream to the downstream side. This makes turbulentcurrents or air bubbles unlikely to form inside the casing, and thusensures a smooth water current. The electrodes are less likely to remainuneluted under the cover of air bubbles. Metal ions quickly leave theelectrodes, and do not return thereto, resulting in enhanced ion elutionefficiency.

According to the present invention, in the ion elution unit constructedas described above, a water inflow port and a water outflow port areformed in the casing of the ion elution unit, and the water outflow portis located in the lowest position within the interior space of thecasing. With this construction, since the outflow port is located in thelowest position within the interior space of the casing, when the supplyof water to the ion elution unit is stopped, all the water inside itflows out of it through the outflow port. This prevents water remaininginside the casing from being frozen in cold weather and causing failureor destruction of the ion elution unit.

According to the present invention, in the ion elution unit constructedas described above, terminals that are so laid as to run from theelectrodes out of the casing of the ion elution unit are formed in aposition inward of the ends of the electrodes located on the upstreamside with respect to the water current flowing through the inside of thecasing. With this construction, the terminals are indeed upstream-sideparts of the electrode but are not at the very ends thereof; that is,they are formed inward of the upstream-side ends of the electrode. Thisprevents the wear that has started at the ends of the electrodes fromreaching the terminals and making them break at the bases thereof.

According to the present invention, in the ion elution unit constructedas described above, the terminals that are so laid as to run out of thecasing of the ion elution unit are formed integrally with theelectrodes. With this construction, since the electrodes and theterminals are formed integrally, as opposed to when separate metalcomponents are joined together, no potential difference appears betweenthe electrodes and the terminals, and thus no corrosion occurs there.Moreover, integrally forming these helps simplify the manufacturingprocess.

According to the present invention, in the ion elution unit constructedas described above, the terminals that are so laid as to run from theelectrodes out of the casing of the ion elution unit have parts thereoflocated inside the casing protected with a sleeve made of an insulatingmaterial. With this construction, the parts of the terminals locatedinside the casing are protected with a sleeve made of an insulatingmaterial, and thus do not wear as a result of energization. Thisprevents the terminals from breaking in the middle of use.

According to the present invention, in the ion elution unit constructedas described above, the terminals laid from the electrodes are so formedas to penetrate the bottom wall of the case of the ion elution unit andprotrude downward. With this construction, even when condensation occurson the outer surface of the casing as a result of water vapor makingcontact with the casing or the casing being cooled as water is passedtherethrough, the condensed water flows down along the cable connectedto the terminals, and thus does not collect at the boundaries betweenthe terminals and the casing. This prevents the terminals from beingshort-circuited by condensed water.

According to the present invention, in an ion elution unit as describedabove, an anode electrode is made of silver, copper, zinc or an alloy ofsilver and copper. With this construction, silver ions eluted from asilver electrode, copper ions eluted from a copper electrode and zincions eluted from a zinc electrode are exploited their excellentsterilizing effect, even on mold.

According to the present invention, in an ion elution unit as describedabove, both anode electrode and cathode electrode are made of silver,copper, zinc or an alloy of silver and copper. With this construction,silver ions eluted from a silver electrode, copper ions eluted from acopper electrode and zinc ions eluted from a zinc electrode areexploited their excellent sterilizing effect, even on mold. This effectis unchanged when the polarity of the electrodes is reversed.

According to the present invention, in an ion elution unit as describedabove, the polarity of the electrodes is reversed cyclically. With thisconstruction, a problem that the surface of electrode is covered with athick layer of scale deposited through the use of long period andcurrent is subjected to be restricted, is avoidable. Also a problem of“one-sided depletion,” in which only one electrode being used as ananode is consumed at a rate faster than the other, is avoidable.

According to the present invention, an ion elution unit as describedabove is incorporated in an appliance so that the appliance uses watermixed with metal ions generated by the ion elution unit. With thisconstruction, it is possible to use water mixed with metal ionsgenerated by the ion elution unit. For example, if the appliance is adish washing machine, it is possible to treat eating utensils withantimicrobial treatment using metal ions and thereby enhance hygiene. Ifthe appliance is a humidifier, it is possible to prevent proliferationof bacteria and algae in the water stored in its water tank and therebyprevent bacteria and algae spores from being spread into the air andcausing an infection or allergy in a person who inhaled them.

According to the present invention, in the appliance constructed asdescribed above, the appliance is a washer. With this construction, itis possible to treat with antimicrobial treatment using metal ions andthereby prevent proliferation of bacteria and mold and generation of anoffensive smell.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a vertical sectional view of a washer embodying the presentinvention.

FIG. 2 is a schematic vertical sectional view of a water feed mouth.

FIG. 3 is a partial top view of an interior of the washer.

FIG. 4 is a top view of an ion elution unit.

FIG. 5 is a vertical sectional view taken along line A-A shown in FIG.4.

FIG. 6 is a vertical sectional view taken along line B-B shown in FIG.4.

FIG. 7 is a horizontal sectional view of the ion elution unit.

FIG. 8 is a perspective view of an electrode.

FIG. 9 is a circuit diagram of a drive circuit of the ion elution unit.

FIG. 10 is a flow chart of an entire session of laundry washing;

FIG. 11 is a flow chart of a washing process.

FIG. 12 is a flow chart of a rinsing process.

FIG. 13 is a flow chart of a squeezing process.

FIG. 14 is a flow chart of a final rinsing process.

BEST MODE FOR CARRYING OUT THE INVENTION

An embodiment of the present invention will be described with referenceto Figures.

FIG. 1 is a vertical sectional view showing the overall construction ofa washer 1. The washer 1 is of an automatic type, and has a cabinet 10.The box-shaped cabinet 10 is formed of metal or synthetic resin, and hasopenings at its top and bottom. The top opening of the cabinet 10 iscovered with a top plate 11, which is formed of synthetic resin and isfixed to the cabinet 10 with screws. In FIG. 1, front and rear of thewasher 1 point leftward and rightward, respectively. A rear portion of atop surface of the top plate 11 is covered with a back panel 12, whichis formed of synthetic resin and is fixed to the cabinet 10 or the topplate 11 with screws. The bottom opening of the cabinet 10 is coveredwith a base 13, which is formed of synthetic resin and is fixed to thecabinet 10 with screws. None of the screws mentioned thus far are shownin the figure.

Feet 14 a and 14 b for supporting the cabinet 10 on a floor are disposedat the four corners of the base 13. The rear feet 14 b are fixed feetintegrally formed with the base 13. The front feet 14 a areheight-adjustable screw feet, and turning them levels the washer 1.

The top plate 11 has a laundry inlet opening 15 through which laundry isput in a washing tub described later. The laundry inlet opening 15 iscovered with a lid 16 from above. The lid 16 is coupled to the top plate11 with a hinge 17 so as to be pivotable in a vertical plane.

A water tub 20 and a washing tub 30 that serves also as a squeezing tubare disposed inside the cabinet 10. Both the water tub 20 and thewashing tub 30 are shaped in a cylindrical cup open at its top, and thetwo tubs are arranged concentrically with their axes vertical and withthe washing tub 30 placed inside the water tub 20. The water tub 20 issuspended from the cabinet 10 with suspension members 21. The suspensionmembers 21 connect a lower outer surface of the water tub 20 to fourinner corners of the cabinet 10, and support the water tub 20 in such away that it can swing in a horizontal plane.

The washing tub 30 has a circumferential wall that widens upward with agentle taper. This circumferential wall has a plurality of drain holes31 formed in a ring-shaped arrangement around its topmost portion, andhas, other than these drain holes, no opening that permits passage ofliquid. The washing tub 30 is of so-called “holeless” type. Aring-shaped balancer 32 is attached to a rim of the top opening of thewashing tub 30 to suppress vibration produced by the washing tub 30 whenit rotates at high speed for squeezing of laundry. Inside the washingtub 30, on its bottom surface, a pulsator 33 is disposed to produce acurrent of washing or rinsing water inside the tub 30.

The water tub 20 has a drive unit 40 fitted to its bottom surface frombelow. The drive unit 40 includes a motor 41, a clutch mechanism 42, anda brake mechanism 43, and has a squeezing spindle 44 and a pulsatorspindle 45 protruding from its center upward. The squeezing spindle 44and the pulsator spindle 45 form a double-spindle structure, with thepulsator spindle 45 placed inside the squeezing spindle 44. The twospindles both penetrate the water tub 20. The squeezing spindle 44 isthen connected to the washing tub 30 so as to support it. On the otherhand, the pulsator spindle 45 further penetrates the washing tub 30, andis then connected to the pulsator 33 to support it. Sealing members forpreventing leakage of water are disposed between the squeezing spindle44 and the water tub 20 and between the squeezing spindle 44 and thepulsator spindle 45.

A water feed valve 50, which is operated electro-magnetically, isdisposed inside a space below the back panel 12. The water feed valve 50has a connection pipe 51 that penetrates the back panel 12 to extendupward. A water feed hose (not shown) through which to supply cleanwater such as tap water to the washer is connected to the connectionpipe 51. The water feed valve 50 feeds water to a water feed mouth 53 ina shape of container that is placed above the inside of the water tub20. The water feed mouth 53 has a structure as shown in FIG. 2.

FIG. 2 is a schematic vertical sectional view of the water feed mouth53. The water feed mouth 53 has an opening in its front, and through theopening, a drawer 53 a is inserted. The drawer 53 a has its interiordivided into a plurality of sections (the embodiment of the present hastwo sections, that is, a left-hand section and a right-hand section).The left-hand section is a detergent chamber 54 that serves as a storagespace for detergent. The right-hand section is a treatment agent chamber55 that serves as a storage space for treatment agent for laundrywashing. A bottom of the detergent chamber 54 is provided with a wateroutlet 54 a which is open toward an inside of the water feed mouth 53. Asiphon 57 is disposed in the treatment agent chamber 55. The water feedmouth 53 has, below the bottom of the drawer 53 a, a water outlet 56through which water is fed into the washing tub 30.

The siphon 57 is composed of an inner pipe 57 a that extends verticallyupward from a bottom surface of the treatment agent chamber 55 and acap-shaped outer pipe 57 b with which the inner pipe 57 a is capped.Between the inner pipe 57 a and the outer pipe 57 b is left a gap thatpermits passage of water. The inner pipe 57 a, at its bottom, is open toa bottom of the water feed mouth 53. A predetermined gap is kept betweena bottom end of the outer pipe 57 b and a bottom surface of thetreatment agent chamber 55 so as to serve as a water inlet. When wateris poured into the treatment agent chamber 55 up to a level higher thana top end of the inner pipe 57 a, a principle of siphon works to causewater to flow through the siphon 57 out of the treatment agent chamber55 and then drop to the bottom of the water feed mouth 53, water is thenpoured into the washing tub 30 through the water outlet 56.

The water feed valve 50 is composed of a main water feed valve 50 a anda sub water feed valve 50 b. The main water feed valve 50 a allowsrelatively large flow of water, while the sub water feed valve 50 ballows relatively small flow of water. Setting the flow of water largeor small is achieved by making the internal structure of the main waterfeed valve 50 a and that of the sub water feed valve 50 b be differentfrom each other, or by making the internal structures of both valvessame and combining them with flow-limiting members having differentthrottling ratio. The connection pipe 51 is shared between the main andsub water feed valves 50 a and 50 b.

The main water feed valve 50 a is connected to an opening in a ceilingof the water feed mouth 53 by way of a main water feed passage 52 a.This opening is open toward the detergent chamber 54, so that a largeamount of water flow from the main water feed valve 50 a is poured intothe detergent chamber 54 through the main water feed passage 52 a. Thesub water feed valve 50 b is connected to the opening in the ceiling ofthe water feed mouth 53 by way of a sub water feed passage 52 b. Thisopening is open toward the treatment agent chamber 55, so that a smallamount of water flow from the sub water feed valve 50 b is poured intothe treatment agent chamber 55 through the sub water feed passage 52 b.That is, a passage that runs from the main water feed valve 50 a throughthe detergent chamber 54 to the washing tub 30 is separate from apassage that runs from the sub water feed valve 50 b through thetreatment agent chamber 55 to the washing tub 30.

Back in FIG. 1, to the bottom of the water tub 20 is fitted a drain hose60 through which water is drained out of the water tub 20 and thewashing tub 30. Water flows into the drain hose 60 from drain pipes 61and 62. The drain pipe 61 is connected to a rather peripheral portion ofthe bottom surface of the water tub 20, and the drain pipe 62 isconnected to a rather central portion of the bottom surface of the watertub 20.

Inside the water tub 20, on its bottom surface, there is fixed aring-shaped partition wall 63 in such a way as to enclose the portion ofthe water tub 20 where the drain pipe 62 is connected to it. Thepartition wall 63 is fitted with a circular sealing member 64 at itstop. The sealing member 64 is kept in contact with a circumferentialsurface of a disk fixed to an outer bottom surface of the washing tub 30so as to form a separate drain space 66 between the water tub 20 and thewashing tub 30. The drain space 66 communicates with an interior of thewashing tub 30 through a drain outlet 67 formed in the bottom of thewashing tub 30.

The drain pipe 62 is provided with a drain valve 68 that is operatedelectro-magnetically. In a portion of the drain pipe 62, on the upstreamside of the drain valve 68, an air trap 69 is disposed. A lead pipe 70extends from the air trap 69. The lead pipe 70 is, at its top end,connected to a water level switch 71.

A controller 80 is disposed in a front portion of the cabinet 10,beneath the top plate 11. The controller 80 receives instructions fromusers via an operation/display panel 81 disposed on the top surface ofthe top plate 11, and sends operation commands to the drive unit 40, thewater feed valve 50, and the drain valve 68. The controller 80 alsosends display commands to the operation/display panel 81. The controller80 includes a drive circuit for driving an ion elution unit describedlater.

How the washer 1 operates will now be described. First, the lid 16 isopened, and laundry is put into the washing tub 30 through the laundryinlet opening 15. The drawer 53 a is pulled out from the water feedmouth 53 and a detergent is put in the detergent chamber 54 in thedrawer 53 a. A treatment agent (softening agent) is put in the treatmentagent chamber 55. The treatment agent (softening agent) can be put therein the middle of a laundry washing session, or may not be put whenunnecessary. After the detergent and the treatment agent (softeningagent) are set, the drawer 53 a is pushed back into the water feed mouth53.

After the detergent and the treatment agent (softening agent) are madeready for addition in this way, the lid 16 is closed, and a desiredcourse of laundry washing is selected by operating a group of operationbuttons on the operation/display panel 81. By pressing a start buttonsubsequently, a session of laundry washing is executed according to theflow charts shown in FIGS. 10 through 13.

FIG. 10 is a flow chart showing the entire session of laundry washing.In step S201, laundry washing is started at a previously set time.Whether a timer-started operation is selected or not is checked. If atimer-started operation is selected, the flow proceeds to step S206; ifnot, the flow proceeds to step S202.

In step S206, whether the operation start time has come or not ischecked. If the operation start time has come, the flow proceeds to stepS202.

In step S202, whether a washing process is selected or not is checked.If a washing process is selected, the flow proceeds to S300. How thewashing process in step S300 is executed will be described later withreference to the flow chart shown in FIG. 11. On completion of thewashing process, the flow proceeds to step S203. If no washing processis selected, the flow proceeds directly from step S202 to step S203.

In step S203, whether a rinsing process is selected or not is checked.If a rinsing process is selected, the flow proceeds to S400. How therinsing process in step S400 is executed will be described later withreference to the flow chart shown in FIG. 12. In FIG. 10, the rinsingprocess is repeated three times, and each step of the process is shownwith a step number with a suffix number added such as “S400-1,” “S400-2”and “S400-3.” The number of times of the rinsing process is set atusers' discretion. In this case, “S400-3” is a final rinsing process.

On completion of the rinsing process, the flow proceeds to step S204. Ifno rinsing process is selected, the flow proceeds directly from stepS203 to step S204.

In step S204, whether a squeezing process is selected or not is checked.If a squeezing process is selected, the flow proceeds to S500. How thesqueezing process in step S500 is executed will be described later withreference to the flow chart shown in FIG. 13. On completion of thesqueezing process, the flow proceeds to step S205. If no squeezingprocess is selected, the flow proceeds directly from step S204 to stepS205.

In step S205, termination of operation of the controller 80, inparticular a processing unit (microcomputer) therein, is automaticallyexecuted in accordance with a predetermined procedure. In addition, thecompletion of laundry washing session is indicated by sounding anoperation-completion beep. On completion of all the operations, thewasher 1 goes back into a stand-by state in preparation for a newsession of laundry washing.

Next, with reference to FIGS. 11 through 13, the individual processes ofwashing, rinsing, and squeezing will be described.

FIG. 11 is a flow chart of the washing process. In step S301, the waterlevel inside the washing tub 30 as sensed by the water level switch 71starts being monitored. In step S302, whether laundry amount sensing isselected or not is checked. If laundry amount sensing is selected, theflow proceeds to step S308; if not, the flow proceeds directly from stepS302 to S303.

In step S308, the amount of laundry is measured on the basis of load ofrotation of the pulsator 33. On completion of laundry amount sensing,the flow proceeds to step S303.

In step S303, the main water feed valve 50 a is opened, and water ispoured into the washing tub 30 through the water feed mouth 53. Thedetergent agent put into the detergent chamber 54 is mixed with water,and enters the washing tub 30. The drain valve 68 remains closed. Whenthe water level switch 71 detects the set water level, the main waterfeed valve 50 a is closed. The flow then proceeds to step S304.

In step S304, a preparatory operation is performed. The pulsator 33 isrotated repeatedly in forward and then reverse directions to agitate thelaundry and water so that the laundry is fully dipped in water. Thispermits the laundry to absorb an ample amount of water, and permits airtrapped in many parts of the laundry to escape. If, as a result of thepreparatory operation, the water level as detected by the water levelswitch 71 becomes lower than at the beginning, then, in step S305, themain water feed valve 50 a is opened to supply additional water torecover the set water level.

If a course of laundry washing including “cloth type sensing” isselected, when the preparatory operation is performed, the type of clothis sensed. On completion of the preparatory operation, the change of thewater level from the set water level is detected, and, if the drop inthe water level is greater than a predetermined amount, the laundry isjudged to be of the highly water-absorbent cloth type.

When, in step S305, the set water level is stably obtained, the flowproceeds to step S306. According to the settings made by users, themotor 41 rotates the pulsator 33 in a predetermined pattern so as toproduce, in the washing tub 30, a main current of water for washing.With this main current of water, the laundry is washed. The squeezingspindle 44 remains braked by the brake mechanism 43 so that, even whenthe washing water and the laundry move, the washing tub 30 does notrotate.

On completion of the period in which the laundry is washed with the maincurrent of water, the flow proceeds to step S307. In step S307, thepulsator 33 is rotated repeatedly in the forward and then reversedirections at short time intervals. This permits the laundry to loosen,and thereby permits it to spread evenly in the washing tub 30. This isdone in preparation for squeezing rotation of the washing tub 30.

Next, with reference to the flow chart shown in FIG. 12, the rinsingprocess will be described. First, in step S500, the squeezing process isexecuted, of which a description will be given later with reference tothe flow chart shown in FIG. 13. On completion of squeezing, the flowproceeds to step S401. In step S401, the main water feed valve 50 a isopened, and water is supplied up to the set water level.

On completion of the supply of water, the flow proceeds to step S402. Instep S402, a preparatory operation is performed. During the preparatoryoperation performed in step S402, laundry getting attached to thewashing tub 30 in step S500 (squeezing process) is separated, soakedinto water so that the laundry thoroughly absorbs water.

On completion of the preparatory operation, the flow proceeds to stepS403. If, as a result of the preparatory operation, the water level asdetected by the water level switch 71 becomes lower than at thebeginning, the main water feed valve 50 a is opened to supply additionalwater to recover the set water level.

After recovering the set water level in step S403, the flow thenproceeds to step S404. According to the settings made by users, themotor 41 rotates the pulsator 33 in a predetermined pattern so as toproduce, in the washing tub 30, a main current of water for rinsing.With this main current of water, the laundry is rinsed. The squeezingspindle 44 remains braked by the brake mechanism 43 so that, even whenthe rinsing water and the laundry move, the washing tub 30 does notrotate.

On completion of the period in which the laundry is rinsed with the maincurrent of water, the flow proceeds to step S406. In step S406, thepulsator 33 is rotated repeatedly in the forward and then reversedirections at short time intervals. This permits the laundry to loosen,and thereby permits it to spread evenly in the washing tub 30. This isdone in preparation for squeezing rotation.

In the above description, rinsing is assumed to be performed withrinsing water stored in the washing tub 30. This is called “rinsing withstored water.” It is, however, also possible to perform rinsing withalways replenishing fresh water, which is called “rinsing with pouringwater,” or to perform rinsing with water kept supplied from the waterfeed mouth 53 while the washing tub 30 is rotated at a low speed, whichis called “shower rinsing.”

In the final rinsing process, different sequence from the above isexecuted. This will be described in details later.

Next, with reference to the flow chart shown in FIG. 13, the squeezingprocess will be described. First, in step S501, the drain valve 68 isopened. The washing water in the washing tub 30 is drained through thedrain space 66. The drain valve 68 remains open during the squeezingprocess.

When most of the washing water has exited from the laundry, the clutchmechanism 42 and the brake mechanism 43 are switched over. The timingfor switching over of the clutch mechanism 42 and the brake mechanism 43is either before or at the same time of starting of draining of water.The motor 41 now rotates the squeezing spindle 44. This causes thewashing tub 30 to start squeezing rotation. The pulsator 33 rotatestogether with the washing tub 30.

When the washing tub 30 rotates at a high speed, the laundry is pressedagainst the inner circumferential wall of the washing tub 30 by thecentrifugal force. The washing water present in the laundry also gatherson the inner surface of the circumferential wall of the washing tub 30,and, since the washing tub 30 widens upward in a tapered shape asdescribed earlier, the washing water driven by the centrifugal forcerises along the inner surface of the washing tub 30. When the washingwater reaches the top end of the washing tub 30, it is drained throughthe drain holes 31. The washing water that has exited from the drainholes 31 hits the inner surface of the water tub 20, and then flows downalong the inner surface of the water tub 20 to the bottom of the watertub 20. The washing water is then drained out of the cabinet 10 throughthe drain pipe 61 and then through the drain hose 60.

In the flow shown in FIG. 13, after squeezing is performed at arelatively low speed in step S502, squeezing is performed at high speedin step S503. On completion of step S503, the flow proceeds to stepS504. In step S504, the supply of electric power to the motor 41 isstopped and termination operation is done for stopping.

The washer 1 is furnished with an ion elution unit 100. The ion elutionunit 100 is connected to the downstream side of the main water feed pipe52 a. Now, with reference to FIGS. 3 through 9, the structure andfunctions of the ion elution unit 100 and the purpose for which it isincorporated in the washer 1 will be described.

FIG. 3 is a partial top view indicating the layout of the ion elutionunit 100 and the water feed mouth 53. The ion elution unit 100 isconnected directly to the main water feed valve 50 a and the water feedmouth 53 on both ends. In other words, the ion elution unit 100independently composes the entire main water feed passage 52 a. The subwater feed passage 52 b is constructed by connecting the pipe, whichprotrudes from the water feed mouth 53, to the sub water feed valve 50 bwith a hose. In the schematic view of FIG. 1, the water feed valve 50,the ion elution unit 100 and the water feed mouth 53 are arranged inline with front-to-rear axis of the washer 1. However, in an actualwasher, they are not arranged in that way but arranged in line withleft-to-right axis of the washer 1.

FIG. 4 through FIG. 8 shows the structure of the ion elution unit. FIG.4 is a top view. FIG. 5 is a vertical sectional view taken along lineA-A shown in FIG. 4. FIG. 6 is also a vertical sectional view takenalong line B-B shown in FIG. 4. FIG. 7 is a horizontal sectional view.FIG. 8 is a perspective view of an electrode.

The ion elution unit 100 has a casing 110 formed of transparent ortranslucent, colorless or colored synthetic resin or opaque syntheticresin. The casing 110 is composed of a casing body 110 a having anopening at the top and a lid 110 b which closes the opening at the top.(See FIG. 5.) The casing 110 a is shaped as long and narrow, containinga water inlet 111 at one end of the longitudinal direction and a wateroutlet 112 at the other end. The water inlet 111 and the water outlet112 are pipe-shaped. Cross-sectional area of the water outlet 112 issmaller than that of the water inlet 111.

The casing 110 is arranged with its longitudinal direction beinghorizontal. The casing body 110 a arranged horizontally in this way hasa bottom that inclines gradually toward the water outlet 112. (See FIG.5.) In other words, the water outlet 112 is located at the lowest levelin an internal space of the casing 110.

The lid 110 b is fixed to the casing body 110 a with four screws 170.(See FIG. 4.) A seal ring 171 is inserted between the casing body 110 aand the lid 110 b. (See FIG. 5.)

Inside the casing 110, two plate electrodes 113 and 114 are arranged soas to be parallel to the water current flowing from the water inlet 111toward the water outlet 112, facing each other. When a predeterminedvoltage is applied to the electrodes 113 and 114 with the casing 110filled with water, metal ions of the metal of which the electrodes 113and 114 are formed are eluted from whichever of them is at the anodeside at the moment. For an example, the electrodes 113 and 114 may be soconstructed that plates of silver each measuring 2 cm×5 cm and about 1mm thick are arranged about 5 mm apart from each other.

Material of the electrodes 113 and 114 is not limited to silver. Anymetal can be the material as long as it is a source for antimicrobialmetal ions. Other than silver, copper, an alloy of silver and copper,zinc or the like can be selected. Silver ions eluted from a silverelectrode, copper ions eluted from a copper electrode and zinc ionseluted from a zinc electrode show an excellent sterilizing effect, evenon mold. From an alloy of silver and copper, silver and copper ions canbe eluted simultaneously.

As for the ion elution unit 100, it is possible to select either elutionor non-elution by whether a voltage is applied or not. Moreover, anamount of elution of metal ions can be controlled by controllingelectric current or the time for applying a voltage. Compared with amethod of eluting metal ions from zeolite or other metal ion carriers,it is convenient because it is possible to electrically select whetherthe metal ions are added or not and to electrically adjust theconcentration of the metal ions.

The electrodes 113 and 114 are not arranged completely in parallel. Inthe plane view, they are arranged to be tapered, having the spacebetween them becomes narrower from the upstream toward the downstreamalong the water current flowing through the inside of the casing 110, inother words, from the water inlet 111 toward the water outlet 112. (SeeFIG. 7.)

The plan-view shape of the casing body 110 a is also narrowed from oneend having the water inlet 111 to the other end having the water outlet112. Namely, the cross-sectional area in the internal space of thecasing 110 gradually decreases from the upstream side toward thedownstream side.

The electrodes 113 and 114 have both rectangular profile, and terminals115 and 116 are provided thereto respectively. The terminals 115 and 116are disposed at portions inside of the edges of the electrodes 113 and114 on the upstream side, hanging down from the lower edge of theelectrodes 113 and 114 respectively.

The electrode 113 and the terminal 115 are formed integrally from thesame metal, and the electrode 114 and the terminal 116 are formedintegrally from the same metal. The electrodes 115 and 116 are led tothe bottom of the casing body 110 a through a hole formed in a bottomwall of the casing body 110 a. Where the terminals 115 and 116 protrudeout of the casing 110 a, as shown in an enlarged figure in FIG. 6, awatertight seal 172 is installed. The watertight seal 172 forms a doublesealing construction together with a second sleeve 175 described laterso as to prevent water from leaking from this portion.

At the bottom of the casing 110 a, an insulating wall 173, whichisolates the terminals 115 and 116, is integrally formed. (See FIG. 6.)The terminals 115 and 116 are connected to a drive circuit within thecontroller 80 by way of a cable (not shown).

Of the terminals 115 and 116, portions remaining in the casing 110 areprotected by a sleeve made of insulation material. Two types of sleevesare used. One sleeve 174 is made of synthetic resin and engaged into theroots of the terminals 115 and 116. A part of the first sleeve 174spreads to one side of the electrodes 113 and 114, forming projectionson the side of these portions and fitting these projections to thethrough holes made in the electrodes 113 and 114. This helps prevent theelectrodes 113 and 114 from coming out of the sleeve 174. The secondsleeve 175 is made of soft rubber and fills the gap between the firstsleeve 174 and the bottom wall of the casing body 110 a, thus preventingwater from leaking through the gap between the second sleeve 175 and thecasing body 110 a and through the gaps between the second sleeve 175 andthe electrodes 113 and 114.

As mentioned above, the terminals 115 and 116 are located on theupstream side of the electrodes 113 and 114. The upstream sides of theelectrodes 113 and 114 are supported by the first sleeve 174, which isengaged to the terminals 115 and 116. On the inner surface of the lid110 b, a support 176 in a shape of a fork is formed so as to fit to theposition of the first sleeve 174. (See FIG. 6.) This support 176 catchesthe upper edge of the first sleeve 174 and becomes a rigid support,together with the second sleeve 175 filling the gap between the firstsleeve 174 and the casing body 110 a. The fork-shaped support 176catches the electrodes 113 and 114 with long and short fingers, by whichthe electrodes 113 and 114 can maintain an appropriate space betweeneach other on the side of the lid 110 b.

The downstream sides of the electrodes 113 and 114 are also supported bythe support formed on the inner surface of the casing 110. A fork-shapedsupport 177 rises from the bottom surface of the casing body 110 a.Also, a fork-shaped support 178 hangs down from the ceiling of the lid110 b to face the support 177. (See FIGS. 5 and 8.) The electrodes 113and 114 are caught by the supports 177 and 178 at the lower and upperedges on the downstream side respectively so as not to move.

As shown in FIG. 7, the electrodes 113 and 114 are so arranged that thesurfaces opposite to the surfaces that are facing each other keep aspace from the inner surface of the casing 110. Moreover, as shown inFIG. 5, the electrodes 113 and 114 are so arranged as to keep a spacebetween their upper and lower edges and the inner surface of the casing110. (Portions which are in contact with the supports 176, 177 and 178are exceptions.) Additionally, as shown in either of FIG. 7 and FIG. 5,a space is made between the upstream and downstream side edges of theelectrodes 113 and 114 and the inner surface of the casing 110.

When it is necessary to make the width of the casing 110 much smaller,it is possible to construct the electrodes 113 and 114 in such a mannerthat the surfaces opposite to the surfaces that are facing each otherare attached firmly to the inner wall of the casing 110.

In order to prevent foreign objects from getting contact with theelectrodes 113 and 114, a strainer of a metal mesh is mounted on theupstream side of the electrodes 113 and 114. As shown in FIG. 2, astrainer 180 is placed in the connection pipe 51. The strainer 180 isfor the purpose of preventing foreign objects from intruding into thewater feed valve 50, and it also serves as an upstream strainer of theion elution unit 100.

A strainer of a metal mesh 181 is mounted to the downstream side of theelectrodes 113 and 114. The strainer 181 prevents broken pieces of theelectrodes 113 and 114 from flowing out when they are thinned out andbroken due to being used for a long time. The water outlet 112 can beselected as a site for mounting the strainer 181, for example.

The locations of the strainers 180 and 181 are not limited to the above.As long as the conditions of mounting on “the upstream side of theelectrode” and on “the downstream side of the electrode” are satisfied,they can be placed at any location in the water feed passage. Thestrainers 180 and 181 are removable so that foreign objects they catchcan be removed or substances contributing to clogging can be cleared of.

FIG. 9 shows the drive circuit 120 for the ion elution unit 100. Atransformer 122 is connected to commercially distributed electric power121 so as to step down 100 V to a predetermined voltage. The outputvoltage of the transformer 122 is rectified by a full-wave rectifiercircuit 123, and is then formed into a constant voltage by a constantvoltage circuit 124. To the constant voltage circuit 124 is connected aconstant current circuit 125. The constant current circuit 125 operatesin such a way as to supply a constant current to the electrode drivecircuit 150 described later without being influenced by variation in theresistance through the electrode drive circuit 150.

To the commercially distributed electric power 121 is also connected, inparallel with the transformer 122, a rectifying diode 126. The outputvoltage of the rectifying diode 126 is smoothed by a capacitor 127, isthen formed into a constant voltage by a constant voltage circuit 128,and is then supplied to a microcomputer 130. The microcomputer 130controls the starting of a triac 129 connected between one end of theprimary coil of the transformer 122 and the commercially distributedelectric power 121.

The electrode drive circuit 150 is composed of NPN-type transistors Q1to Q4, diodes D1 and D2, and resistors R1 to R7. These areinterconnected as shown in the figure. The transistor Q1 and the diodeD1 form a photocoupler 151, and the transistor Q2 and the diode D2 forma photocoupler 152. The diodes D1 and D2 are photodiodes, and thetransistors Q1 and Q2 are phototransistors.

The microcomputer 130 feeds a high-level voltage to a line L1 and alow-level voltage (or zero voltage, namely, “off”) to a line L2. Then,the diode D2 turns on, and this causes the transistor Q2 to turn on.When the transistor Q2 turns on, a current flows through the resistorsR3, R4, and R7, and this causes a bias to be applied to the base of thetransistor Q3. Thus, the transistor Q3 turns on.

On the other hand, the diode D1 is off, and thus the transistors Q1 isoff, and accordingly the transistor Q4 is off. In this state, a currentflows from the anode-side electrode 113 to the cathode-side electrode114. As a result, in the ion elution unit 100, there are produced metalions as positively-charged ions together with negatively-charged ions.

When an electric current is passed through the ion elution unit 100 inone direction for a long time, the electrode 113, which is at the anodeside in FIG. 9, wears off, while the electrode 114, which is at thecathode side, collects impurities in water in the form of scalesdeposited on it. This degrades the performance of the ion elution unit100. In order to avoid this, the electrode drive circuit 150 can beoperated in a compulsory electrode-cleaning mode.

In the compulsory electrode-cleaning mode, the microcomputer 130switches modes of control so as to invert the voltage applied betweenthe lines L1 and L2 and thereby reverse the current that flows betweenthe electrodes 113 and 114. In this mode, the transistors Q1 and Q4 areon, and the transistors Q2 and Q3 are off. The microcomputer 130 has acounter capability, and switches modes of control as described aboveevery time a predetermined count is reached.

When the resistance through the electrode drive circuit 150, inparticular, the resistance of the electrodes 113 and 114, varies and asa result, for example, the current that flows between the electrodesdecreases, the constant current circuit 125 raises its output voltage tocompensate for the decrease. However, as the total time of useincreases, the ion elution unit 100 eventually reaches the end of itsservice life. When this happens, even if the mode of control is switchedto the forcible electrode cleaning mode, or if the output voltage of theconstant current circuit 125 is raised, it is no longer possible tocompensate for the decrease in the current.

In order to cope with this, in the circuit under discussion, the currentthat flows between the electrodes 113 and 114 of the ion elution unit100 is monitored on the basis of the voltage that it produces across theresistor R7. When the current becomes equal to a predetermined minimumcurrent, a current detection circuit 160 detects it. The fact that theminimum current has been detected is transmitted from a photodiode D3,which is a part of a photocoupler 163, through a phototransistor Q5 tothe microcomputer 130. The microcomputer 130 then drives, by way of aline L3, a warning indicator 131 to make it indicate a predeterminedwarning. The warning indicator 131 is provided in the operation/displaypanel 81 or in the controller 80.

Moreover, in order to cope with a fault such as short-circuiting withinthe electrode drive circuit 150, there is provided a current detectioncircuit 161 that detects the current being larger than a predeterminedmaximum current. On the basis of the output of this current detectioncircuit 161, the microcomputer 130 drives the warning indicator 131.Furthermore, when the output voltage of the constant current circuit 125becomes lower than a previously set minimum voltage, a voltage detectioncircuit 162 detects it, and the microcomputer 130 likewise drives thewarning indicator 131.

The metal ions generated by the ion elution unit 100 are poured into thewashing tub in the following manner.

Metal ions and a softening agent to be used as a treatment agent areadded in the final rinsing process. FIG. 14 is a flow chart showing thesequence of the final rinsing. In the final rinsing process, after thesqueezing process of step S500, the flow proceeds to step S420. In step420, whether addition of the treatment material is selected or not ischecked. When “addition of a treatment agent” is selected through aselection operation performed by way of the operation/display panel 81,the flow proceeds to step S421. If not, the flow proceeds to step S401in FIG. 12, and the final rinsing is executed in the same manner as inthe previous rinsing processes.

In step S421, whether the treatment materials to be added are two types,that is metal ions and a softening agent, or not, is checked. When“metal ions and a softening agent” is selected through a selectionoperation performed by way of the operation/display panel 81, the flowproceeds to step S422; if not, the flow proceeds to step S426.

In step S422, both of the main water feed valve 50 a and the sub waterfeed valve 50 b are opened, and water flows into both of the main waterfeed passage 52 a and the sub water feed passage 52 b.

Step S422 is a process for elution of metal ions. A predetermined amountof water, which is set to be more than the volume of water set for thesub water feed valve 50 b, is flowing, filling the internal space of theion elution unit 100. Simultaneously, the drive circuit 120 applies avoltage between the electrodes 113 and 114, so that ions of the metal ofwhich they are formed are eluted into the water. When the metal formingthe electrodes 113 and 114 is silver, reaction of Ag→Ag⁺+e⁻ occurs onthe anode side and silver ions Ag⁺ are eluted into the water. Theelectric current flowing between the electrodes 113 and 114 is directcurrent. Water to which the metal ions are added flows into thedetergent chamber 54 and then is poured into the washing tub 30 from thewater outlet 54 a by way of the water outlet 56.

From the sub water feed valve 50 b, smaller amount of water than thatfrom the main water feed valve 50 a flows out and is poured into thetreatment agent chamber 55 by way of the sub water feed passage 52 b. Ifa treatment agent (softening agent) has been supplied into the treatmentagent chamber 55, the treatment agent (softening agent) is fed into thewashing tub 30 through the siphon 57 together with water. This additionis performed simultaneously when the metal ions are added. The effect ofa siphon does not occur until the water level inside the treatment agentchamber 55 reaches a predetermined level. This permits the liquidtreatment agent (softening agent) to be held in the treatment agentchamber 55 until the time comes when water is poured into the treatmentagent chamber 55.

When a predetermined amount of water (so much as or more than the amountto cause the effect of a siphon to occur in the siphon 57) is pouredinto the treatment agent chamber 55, the sub water feed valve 50 b isclosed. This step of feeding water, namely, adding a treatment agent, isperformed automatically, irrespective of whether or not a treatmentagent (softening agent) has been put into the treatment agent chamber 55so long as “addition of a treatment agent” is selected.

When a predetermined amount of water containing metal ions has beenpoured into the washing tub 30, and the concentration of metal ions inthe rinsing water is expected to be a predetermined level when watercontaining no metal ions is fed to the set water level, the applicationof a voltage between the electrodes 113 and 114 is stopped. After theion elution unit 100 stops generation of metal ions, the main water feedvalve 50 a continues supplying water and stops water supply when thewater level in the washing tub 30 reaches the set level.

As described above, in step S422, metal ions and a treatment agent(softening agent) are added simultaneously. However, this does notnecessarily mean that the time during which a treatment agent (softeningagent) is poured into the washing tub through an effect of a siphoncompletely overlaps the time while the ion elution unit 100 isgenerating metal ions. Either of the above time may be shifted to beearlier or later than the other. After the ion elution unit 100 stopsgeneration of the metal ions and while water containing no metal ions isadditionally fed, the treatment agent (softening agent) may be added.The point is that it is sufficient so long as the addition of metal ionsand the addition of a treatment agent (softening agent) are executedrespectively in one sequence.

As described before, the terminal 115 is formed to the electrode 113integrally and the terminal 116 is formed to the electrode 114integrally, from the same metal. Therefore, different from a case wheredifferent metals are connected, potential difference does not occurbetween the electrodes and terminals, thus preventing corrosion fromoccurring. Additionally, being formed integrally simplifies themanufacturing process.

The space between the electrodes 113 and 114 is set to be in a taperedmanner, becoming narrower from the upstream side toward the downstreamside. This makes the electrodes 113 and 114 be in line with the flow,and the electrodes 113 and 114 are more likely not generating vibration,thereby even when they wear off and are thinned, they hardly are chippedoff. Moreover, there is no concern for excessive deformation ofelectrodes that might result in a short circuit.

The electrodes 113 and 114 are supported in a manner that a space ismade between them and the inner surface of the casing 110. This helpsprevent a metal layer from growing from the electrodes 113 and 114 tothe inner surface of the casing 110 and causing a short circuit betweenelectrodes.

Although the terminals 115 and 116 are formed integrally to theelectrodes 113 and 114 respectively, the electrodes 113 and 114 areeventually depleted as a result of use. However, the terminals 115 and116 should be kept from depletion. In an embodiment of the present, theportions of the terminals 115 and 116 located inside the casing 110 areprotected by the sleeves 174 and 175 made of insulating material, andare guarded from depletion caused by electric conduction. This helpsprevent such situation as the terminals 115 and 116 are broken in midwayof their use.

In the electrodes 113 and 114, the portions where the terminals 115 and116 are formed are rather deep inside from the edge on the upstreamside. The electrodes 113 and 114 wear off, starting at a portion wherethe space between them has become narrow. In general, depletion occursat the edge portion. Although the terminals 115 and 116 are located inthe upstream side of the electrodes 113 and 114, they are not completelyat the edges, but at rather deep inside portions from the edges.Therefore, it is not necessary to be worried about a situation that thedepletion starting at the edge of an electrode reaches the terminal tocause a breakage of the terminal at its root.

The electrodes 113 and 114 are supported by the first sleeve 174 and thesupport 176 on their upstream sides. On the other hand, the downstreamsides of the electrodes 113 and 114 are supported by the supports 177and 178. Since they are supported rigidly on both upstream side anddownstream sides in this way, the electrodes 113 and 114 do not vibratealthough they are in the water current. As a result, the electrodes 113and 114 do not get broken due to vibration.

The terminals 115 and 116 go through the bottom wall of the casing body110 a to be protruded downward. Therefore, although the external surfaceof the casing 110 is subjected to dew concentration because steam getscontact with the casing 110 a (When warm water in a bath tub is used forwashing, stream is easy to intrude into the interior of the washer 1.)or because the casing 110 is cooled by feeding of water, the water fromdew condensation flows down the cables connected to the terminals 115and 116 and do not stay on the border between the terminals 115 and 116and the casing 110. Therefore, no situation is developed in which ashort circuit occurs between the terminals 115 and 116 due to the watercaused by dew condensation. The casing body 110 a is arranged with thelongitudinal direction on the horizontal line, it is easy to make itconstructed in a manner that the terminals 115 and 116 formed on thesides of the electrodes 113 and 114 protrude downward through the bottomwall of the casing body 110 a.

The cross-sectional area of the water outlet 112 of the ion elution unit100 is smaller than that of the water inlet 111 and has largerresistance to the flow than the water inlet 111. This makes waterentering the casing 110 through the water inlet 111 fill the interior ofthe casing 110 without causing stagnant air and soak the electrodes 113and 114 completely. Therefore, such situation as the electrodes 113 and114 have portions that are unrelated to the generation of metal ions butremain un-melted does not occur.

Not only the cross-sectional area of the water outlet 112 is smallerthan that of the water inlet 111 but also the cross-sectional area ofthe inner space of the casing 110 is gradually decreasing from theupstream side toward the downstream side. This makes generation ofturbulence or air bubble inside the casing 110 be reduced, therebymaking water flow smoothly. Also, this prevents the electrodes partiallynot melted by the existence of air bubble. The metal ions come off theelectrodes 113 and 114 quickly and do not go back to the electrodes 113and 114, thus increasing the efficiency of ion elution.

The ion elution unit 100 is arranged in the main water feed passage 52 afor a large volume of flow where a large amount of water flows. Thispermits the metal ions to be carried out of the casing 110 quickly andprevents them from going back to the electrodes 113 and 114, thusincreasing the efficiency of ion elution.

The water outlet 112 is placed at the lowest level in the inner space ofthe casing 110. Therefore, when feeding of water to the ion elution unit100 is stopped, all the water in the ion elution unit 100 flows outthrough the water outlet 112. In consequence, no such a case occurs aswater remaining in the casing 110 is frozen at a cold time and the ionelution unit 100 fails or breaks.

A strainer 180 is placed on the upstream side of the electrodes 113 and114. This makes it possible that although solid foreign object exists inwater fed to the ion elution unit 100, the foreign object is caught bythe strainer 180, which prevents it from reaching the electrodes 113 and114. Consequently, a foreign object does not damage the electrodes 113and 114, nor cause a short circuit between the electrodes to cause anexcessive electric current or to lead to metal ion generation shortage.

A strainer 181 is placed on the downstream sides of the electrodes 113and 114. If the electrodes 113 and 114 are depleted and become fragiledue to a long-time use and get broken into pieces and the broken piecesflow, the strainer 181 catches these broken pieces so as to prevent themfrom flowing toward the downstream from that point. As a result, brokenpieces of the electrodes 113 and 114 do not damage an object on thedownstream side.

As the embodiment of the present invention, when a washer 1 is furnishedwith the ion elution unit 100, foreign objects or broken pieces ofelectrodes may be attached to laundry if there are no strainers 180 and181. There is a possibility that foreign objects or broken pieces ofelectrodes may spoil or damage laundry, and if laundry where foreignobjects or broken pieces of electrodes remain attached is subjected tosqueezing and drying, a person who wears the laundry later may touchthem and feel uncomfortable or in the worst case, he may get hurt.However, installation of the strainers 180 and 181 can avoid such asituation.

Both of the strainers 180 and 181 do not have to be placed. When it isdetermined that no installation of a strainer causes a problem, one orboth of them can be abolished.

Back in FIG. 14, in step S423, the rinsing water to which the metal ionsand the treatment agent (softening agent) are added is agitated by apowerful water flow (powerful swirl) and thus promotes contact of thelaundry with the metal ions and attachment of the treatment agent(softening agent) to the laundry.

By thoroughly agitating by the powerful swirl, the metal ions and thetreatment agent (softening agent) can be melted uniformly in water andspread to every corner of the laundry. After agitation by the powerfulswirl for a predetermined time, the flow proceeds to step S424.

In step S424, the situation is completely changed. Agitation is executedby weak water flow (mild swirl). Its aimed purpose is to make the metalions attached to the surface of laundry to exert their effect. As longas there is a water flow although it is mild, there is no possibility ofusers' misunderstanding that the operation of the washer 1 has beenover. Therefore, agitation is executed mildly. However, if there is amethod to make users realize that the rinsing process is still inprogress, for example, by displaying an indication on theoperation/display panel 81 to evocate the users' attention, it ispermissible to stop agitation and place the water at a standstill.

After a period of mild swirl, which is set to be sufficient for laundryto absorb the metal ions, the flow proceeds to step S425. Here,agitation for ensuring is executed again with using a powerful waterflow (powerful swirl). This helps distribute the metal ions to theportions of laundry where the metal ions have not been spread and makethem attached firmly.

After step S425, the flow proceeds to step S406. In step S406, thepulsator 33 rotates repeatedly in the forward and then reversedirections at short time intervals. This permits the laundry to loosen,and thereby permits it to spread evenly in the washing tub 30. This isdone in preparation for squeezing rotation.

An example is given to show the distribution of time for each step: fourminutes for step S423 (powerful swirl); four minutes and fifteen secondsfor step S424 (mild swirl), five seconds for step S425 (powerful swirl)and one minute and forty seconds for step S406 (even spreading oflaundry). Total time from step S423 to step 406 is ten minutes.

Basically, it is preferable to add metal ions and a treatment agent(softening agent) separately. This is because when the metal ions cometo contact with a component of the softening agent, they change intochemical compounds, thus losing the antimicrobial effect of the metalions. However, quite an amount of metal ions remain in the rinsing watertill the last of rinsing process. Also, the loss of the effect of themetal ions can be compensated to a certain degree by setting theconcentration of the metal ions appropriately. Therefore, by adding themetal ions and the treating agent (softening agent) simultaneously, therinsing time is shortened compared with the case that the metal ions andthe treating agent (softening agent) are separately added for separateprocesses of rinsing, leading to the promotion of household efficiency,although the efficacy of addition of resistance to microbes is reducedslightly.

Although it is inevitable that the metal ions and the treatment agent(softening agent) meet in the washing tub 30, it is desirable to preventthem from getting in contact with each other until they enter thewashing tub 30. In the embodiment of the present invention, metal ionsare added to the washing tub 30 from the main water feed passage 52 athrough the detergent chamber 54. The treatment agent (softening agent)is added to the washing tub 30 from the treatment agent chamber 55.Since the passage for adding the metal ions to the rinsing water is thusseparated from the passage for adding the treatment agent to the rinsingwater, the metal ions and the treatment agent (softening agent) do notget in contact with each other until they meet in the washing tub 30.Consequently, the metal ions do not change into chemical components bygetting contact with the treatment agent (softening agent) of highconcentration and lose their antimicrobial effect.

In the description, the final rinsing is assumed to be performed withrinsing water stored in the washing tub 30. However, it is also possibleto perform the final rinsing by water being poured, namely, in themanner of “rinsing with pouring water.” In this case, the poured watercontains metal ions.

If the laundry does not spread evenly in step S406 and water is pouredagain for “rinsing for correcting uneven spreading of laundry,” metalions are added to the water.

Either of the addition of the metal ions, the first treatment substance,and the addition of a treatment agent (softening agent), the secondtreatment substance, is optional. It is possible not to carry out eitherof the additions or both of the additions. When both additions are notto be executed, the flow proceeds from step S420 to step S401, and thishas already been described. From now on, addition of either of the twotypes of treatment substances will be described.

In step S421, when the treatment substance to be added is not both ofthe two types, the metal ions and the softening agent, it means thatonly one of them is selected for addition. In this case, the flowproceeds to step S426.

In step S426, whether the treatment substance to be added is metal ionor not is checked. When it is determined to be metal ions, the flowproceeds to step S427; if not, the flow proceeds to step S428.

In step S427, the main water feed valve 50 a is opened and water flowsinto the main water feed passage 52 a. The sub water feed valve 50 b isnot opened. When water flows through the ion elution unit 100, the drivecircuit 120 applies a voltage between the electrodes 113 and 114, whichelutes ions of the metal composing the electrodes into the water. Whenit is determined that a predetermined amount of water containing metalions has been poured into the washing tub 30, and a predeterminedconcentration of metal ions in the rinsing water can be obtained byadding water containing no metal to a set water level, application of avoltage to the electrodes 113 and 114 is stopped. After the ion elutionunit 100 stops generation of the metal ions, the main water feed valve50 a continues to feed water until the water level inside the washingtub 30 reaches the set level.

After step S427, the flow proceeds to step S423. After that, in the samemanner as when the metal ions and the treatment agent (softening agent)are added simultaneously, the flow proceeds from S423 (powerful swirl)to step S424 (mild swirl) and then to step S425 (powerful swirl) and tostep S406 (even spreading of laundry.) The mild swirl period can bereplaced with a still period.

If, in step S426, the treatment substance to be added is not metal ions,then the treatment substance is treatment agent (softening agent). Inthis case, the flow proceeds to step 428.

In step 428, both the main water feed valve 50 a and the sub water feedvalve 50 b are opened and water is fed to both of the main water feedpassage 52 a and the sub water feed passage 52 b. However, the ionelution unit 100 is not operated and metal ions are not generated. Aftersufficient water for causing an effect of siphon is supplied to thetreatment agent chamber 55 and the treatment agent (softening agent) isput into the washing tub 30 by way of the siphon 57, the sub water feedvalve 50 b is closed.

After the sub water feed valve 50 b is closed, the main water feed valve50 a continues to feed water and stops feeding when the water levelinside the washing tub 30 reaches a set level.

After step S428, the flow proceeds to step S423. After that, in the samemanner as when metal ions and treatment agent (softening agent) areadded simultaneously, the flow proceeds from S423 (powerful whirl), tostep S424 (mild swirl) and then to step S425 (powerful swirl) and tostep S406 (even spreading of the laundry). The mild swirl period can bereplaced with a still period.

In this way, even when only one type of treatment substances is added,each of the steps from the powerful whirl to the mild swirl and then tothe powerful whirl is to be taken to ensure that the treatment substanceis attached to the laundry. However, since it is not necessary to equalthe step-time distribution for metal ions and that for treatment agent(softening agent), the step-time distribution is adjusted to fit thetype of treatment substance.

In case of a treatment agent (softening agent), it does not take a longtime to attach to the laundry, unlike the case of the metal ions.Therefore, it is possible that after step S428, only step S423 (powerfulwhirl) and step S406 (even spreading of laundry) are taken and step S423(powerful whirl) can be finished within a short time such as twominutes, for example.

In order to operate the ion elution unit 100, constant current circuit125 of the drive circuit 120 controls the voltage, so that the currentflowing between the electrodes 113 and 114 is constant. By this, theamount of eluted metal ions per unit time becomes constant. When theamount of eluted metal ions per unit time is constant, it is possible tocontrol the concentration of metal ions in the washing tub 30 bycontrolling the volume of water flowing through the ion elution unit 100and the time of metal ion elution, thereby the expected concentration ofmetal ions is easily achieved.

The current flowing between the electrodes 113 and 114 is directcurrent. If the current is alternating current, the following phenomenonoccurs. Namely, when the metal ions are silver ions, for example, thesilver ions that have once been eluted go back to the electrodes byreverse reaction, i.e. Ag⁺+e⁻→Ag, when the polarity of the electrodes isreversed. However, in case of direct current, such phenomenon does notoccur.

On either one of the electrodes 113 and 114, if it acts as a cathode,scale is deposited. When direct current continues to flow withoutreversing the polarity and, as a result, the amount of scale depositbecome larger, the current is subjected to be restricted, and the metalion elution does not proceed at the predetermined rate. Moreover, aphenomenon of “one-sided depletion,” in which only one electrode beingused as an anode is consumed at a rate faster than the other. Therefore,the polarity of the electrodes 113 and 114 is reversed cyclically.

Being used for metal ion elution, the electrodes 113 and 114 aregradually depleted, resulting in drop in metal ion elution rate. Whenthey are used for a long time, the metal ion elution rate becomesunstable and the predetermined metal ion elution rate is not obtained.Therefore, the ion elution unit 100 is made replaceable, and when theduration of electrodes 113 and 114 expires, it can be replaced with anew unit. Moreover, users are notified, through the operation/displaypanel 81, the fact that the duration of electrodes 113 and 114 almostexpires and therefore appropriate countermeasures, for example,replacement of the ion elution unit 100, should be adapted.

It is to be understood that the present invention may be carried out inany other manner than specifically described above as an embodiment, andmany modifications and variations are possible within the scope of theinvention.

INDUSTRIAL APPLICABILITY

The present invention finds wide application in situations whereinexploitation of the antimicrobial effect of metal ions is attempted. Anion elution unit according to the present invention can be effectivelycombined not only with a washer but also with a dish-washer, ahumidifier, or any other type of appliance where growth of bacteria andmold needs to be suppressed. As for washers, to all types of washer thanthose of automatic type like the one, such as those having horizontaldrums (e.g. tumbler type), those having slanted drums, those whichfunction also as dryers, and those with two separated tubs, the presentinvention can be applied.

1. An ion elution unit generating metal ions by applying a voltagebetween electrodes, wherein a space is secured between the electrodesand an inner surface of a casing of the ion elution unit.
 2. The ionelution unit according to claim 1, wherein an interval between theelectrodes becomes narrower from an upstream side to a downstream sidewith respect to a water current flowing through an inside of a casing ofthe ion elution unit.
 3. The ion elution unit according to claim 2,wherein terminals that are so laid as to run from the electrodes out ofthe casing of the ion elution unit are disposed on the upstream sidewith respect to the water current flowing through the inside of thecasing, and a supporting portion for supporting downstream-side parts ofthe electrodes is formed on the inner surface of the casing.
 4. The ionelution unit according to claim 2, wherein a water inflow port and awater outflow port are formed in the casing of the ion elution unit, andthe water outflow port is given a smaller cross-sectional area than thewater inflow port.
 5. The ion elution unit according to claim 2, whereina cross-sectional area of an interior space of the casing graduallydecreases from the upstream side to the downstream side.
 6. The ionelution unit according to claim 1, wherein a water inflow port and awater outflow port are formed in the casing of the ion elution unit, andthe water outflow port is located in a lowest position within aninterior space of the casing.
 7. The ion elution unit according to claim1, wherein, of the electrodes, any positive electrode is made of one ofsilver, copper, zinc, or silver-copper alloy.
 8. The ion elution unitaccording to claim 1, wherein, of the electrodes, both positive andnegative electrodes are made of one of silver, copper, zinc, orsilver-copper alloy.
 9. The ion elution unit according to claim 8,wherein polarities of the electrodes are reversed periodically.
 10. Anappliance comprising the ion elution unit according to claim 8, whereinthe metal ions generated by the ion elution unit are used by being addedto water.
 11. An appliance comprising the ion elution unit according toclaim 9, wherein the metal ions generated by the ion elution unit areused by being added to water.
 12. The appliance according to claim 10,wherein the appliance is a washing machine.
 13. The appliance accordingto claim 11, wherein the appliance is a washing machine.
 14. An ionelution unit that generates metal ions by applying a voltage betweenelectrodes, wherein terminals that are so laid as to run from theelectrodes out of a casing of the ion elution unit are formed in aposition inward of ends of the electrodes located on an upstream sidewith respect to a water current flowing through an inside of the casing.15. The ion elution unit according to claim 14, wherein the terminalsthat are so laid as to run out of the casing of the ion elution unit areformed integrally with the electrodes.
 16. The ion elution unitaccording to claim 14, wherein the terminals that are so laid as to runfrom the electrodes out of the casing of the ion elution unit have partsthereof located inside the casing protected with a sleeve made of aninsulating material.
 17. The ion elution unit according to claim 14,wherein the terminals laid from the electrodes are so formed as topenetrate a bottom wall of the casing of the ion elution unit andprotrude downward.
 18. The ion elution unit according to claim 14,wherein, of the electrodes, any positive electrode is made of one ofsilver, copper, zinc, or silver-copper alloy.
 19. The ion elution unitaccording to claim 14, wherein, of the electrodes, both positive andnegative electrodes are made of one of silver, copper, zinc, orsilver-copper alloy.
 20. The ion elution unit according to claim 19,wherein polarities of the electrodes are reversed periodically.
 21. Anappliance comprising the ion elution unit according to claim 19, whereinthe metal ions generated by the ion elution unit are used by being addedto water.
 22. An appliance comprising the ion elution unit according toclaim 20, wherein the metal ions generated by the ion elution unit areused by being added to water.
 23. The appliance according to claim 21,wherein the appliance is0 a washing machine.
 24. The appliance accordingto claim 22, wherein the appliance is a washing machine.